Mesial bite

One of the most uncomfortable deviations of dentoalveolar development is the mesial bite, which in dentistry is also called progeny, or anterial bite. The pathology is characterized by a clear protrusion of the lower jaw anteriorly. The difficulty lies in the fact that, in addition to an aesthetic problem, such occlusion contributes to the appearance of many health problems. In particular, patients with mesial occlusion often develop diseases of the digestive tract and oral cavity, sleep disturbances, headaches, etc. An unpleasant appearance and incorrect facial geometry can cause many psycho-emotional problems. In this article we will talk about the features of the mesial bite. [1]

Epidemiology

At the stage of the formed bite (this occurs from the age of 17 onwards), problems with the dentition mechanism are recorded in about 35% of people (meaning patients who have not been treated for such anomalies before). Among all known dentoalveolar defects, mesial occlusion occurs in about 2-6%. [2] Among them:

• almost 14% against the background of normal jaw development;
• 19% against the background of maxillary underdevelopment;
• 25% with overgrowth of the mandibular body and branches;
• 16% with overgrowth of the mandibular body;
• 3% with overgrowth of the mandibular branch only;
• 18% against the background of a combination of all the listed characteristics.

In older patients, the mesial occlusion of an indefinite shape can be diagnosed based on the existing dentoalveolar symptoms. Clarification of the form is more complicated and requires additional diagnostic measures.

Causes mesial occlusion

A true mesial bite in almost every second case is a congenital disorder (hereditary defect). The problem may be a consequence of the difficult course of the period of bearing the unborn baby, or complicated childbirth associated with the advancement of the child along the birth canal. The true type of malocclusion can be diagnosed already in the first year of a baby's life.

However, heredity is not the only root cause of the formation of a mesial occlusion: the disease can develop after birth. There are a number of prerequisites for this:

• diseases affecting the upper dentition or upper jaw;
• premature or late change of deciduous teeth (this means not only a physiological change, but also one that is associated with the traumatic loss of milk teeth);
• bad children's habits (prolonged holding of fingers in the mouth, use of pacifiers and nipples, etc.);
• incorrect posture of the child during sleep or at the table (for example, resting the chin on the hand, etc.);
• cranial trauma;
• shortened frenum of the tongue;
• disorders associated with the skeletal system, rickets;
• otorhinolaryngological diseases, curvature of the nasal bones, etc.

In some patients, the cause may be jaw osteomyelitis, tumor processes, acromegaly, complications after removal of the palatine cleft.

Despite the abundance of reasons, it must be admitted that the mesial bite after braces can be completely corrected. However, long-term painstaking treatment will be required - usually at least 18 months, and sometimes more. Therefore, the patient is advised to be patient and strictly follow the advice and instructions of his treating doctor.

Risk factors

The appearance of the mesial occlusion is due to a whole combination of factors that affect the dentoalveolar mechanism at different stages of its formation. One of the root causes determining the development of pathology is heredity. Thus, genetic disorders occur in approximately 40-60% of patients with malocclusion.

The second category of persistent unfavorable factors affects during the intrauterine development of the baby and causes the appearance of specific defects - for example, bone curvatures, underdevelopment of the muscles, etc. Disorders of maxillofacial functionality, bad habits also play a role - all these factors significantly increase the risk of developing orthodontic problems.

How can posture affect the quality of the bite? The normal correct position of the body and the spine is accompanied by an optimal ratio of the lower and upper jaws, since there is an interaction of the weight vectors of the lower jaw, cervical muscles, trachea, back, mouth floor. With an adequate distribution of gravity, muscular traction and pressure, the lower jaw is in a position that corresponds to a high-quality bite, and the bony dentition is under a sufficient load. If the posture is incorrect, then there is a change in the equal action of these forces: the mandibular movement is noted, a mesial bite is formed. Resting at night with a soft mattress and a high pillow, putting your hands under your head, etc., often has an adverse effect.

Another important factor is impaired nasal breathing. In such a situation, the patient constantly opens his mouth, the diaphragm of the oral cavity weakens, which leads to a burden on the lower facial segment, the appearance of a double chin, and a change in the jaw ratio.

In general, doctors talk about the following most common adverse factors:

• heredity (there are relatives in the genus with mesial occlusion or other similar disorders);
• underdevelopment, defects of the dentoalveolar mechanism;
• bad habits, sucking on a pacifier, finger, pencil, upper lip, etc.;
• poor posture or curvature of the spinal column;
• impaired function of ENT organs, etc.

We will talk more about the negative influences of external and internal factors later.

Pathogenesis

In mesial occlusion, the anterior teeth close in the opposite direction along the sagittal plane. The depth of this reverse overlap can vary. In especially difficult cases, the cutting edges of the upper anterior teeth are in contact with the mucous tissue of the mandibular alveolar process from the side of the tongue.

It happens that a patient is diagnosed with an open and mesial bite at the same time. The severity of the defect is determined by the size of the sagittal cleft. The lateral teeth are closed in accordance with Engle's third grade. With a complex course of pathology, the closure of the first upper and second lower molars is observed. In some cases, there is a cross bite (one or two-sided lingual).

The external symptoms of a defect can be of different severity, which depends on the form and degree of complexity. A concave facial profile, a massive protruding chin, a "hidden" upper lip, a high face, and a deployed mandibular angle suggest that the mesial bite is related to overdevelopment of the mandible.

Taking into account the scale of the inconsistency of the dentition, experts have identified several degrees of mesial occlusion:

• The first degree involves reverse overlap of the anterior teeth, in which there is mutual contact, or a sagittal gap up to 2 mm, an increase in the angles of the mandible to 1310, an incorrect ratio of the first molars along the sagittal plane up to 5 mm, and impaired localization of individual crowns.
• In the second degree, the width of the sagittal gap up to 10 mm, a disturbed sagittal ratio of the first molars up to 10 mm, an increase in the angles of the lower jaw to 1330, disturbed localization of individual crowns, and maxillary narrowing are found. The simultaneous presence of an open bite is possible.
• In the third degree, the width of the sagittal cleft exceeds 1 cm, there are discrepancies in the sagittal ratio of the first molars within 11-18 mm, the mandibular angle is expanded to 145 degrees.

In general, experts talk about the following underlying causes of mesial occlusion:

• individual features of the osteo-facial system, which are transmitted in an autosomal dominant way of inheritance (occur in about 30% of cases);
• diseases of a woman while carrying a baby;
• birth trauma;
• artificial feeding with inferior mixtures;
• diseases of the musculoskeletal mechanism (in particular, rickets);
• bad habits from childhood;
• enlarged tongue, incorrect functionality of the tongue, shortened frenum;
• dentoalveolar defects;
• enlarged palatine tonsils;
• wrong position during sleep (dropping the chin to the chest, etc.);
• incorrect jaw or dental dimensions;
• maxillary adentia;
• "Extra" teeth in the bottom row.

Symptoms mesial occlusion

The clinical picture with mesial occlusion is diverse. The first signs - both facial and intraoral - during the period of deciduous teeth are always less pronounced than during a permanent bite.

In true mesial occlusion, the symptomatology is presented as a separate symptom complex, which reflects the overdevelopment and specific configuration of the lower jaw.

The upper jaw is of normal size, short, or distal cranial: this can be determined by teleradiography. In some patients, the disproportionate position of the jaws is compensated by their relative position.

Examination of the facial profile reveals the elongation of the mandibular body and the increase in the angle between the ramus and the body. There is a "confluence" of the middle third of the face, with a protruding chin and lower lip. If the mesial bite is combined with an open bite, then the face takes on an elongated appearance, since the size of its lower third increases.

Visual inspection reveals an inappropriate width of the jaw dental arches in the zone of molars and premolars, a shortened anterior segment of the upper arch, a narrowed and shortened upper apical base, and in some cases - upper incisor retrusion and upper canine retention due to their infringement in the upper arch.

In the anterior region, there may be different types of back overlap - both pronounced open overlap with the sagittal interdental cleft, and deep overlap.

In general, external symptoms are most often represented by the following signs:

• "Concave" face;
• discomfort and sounds in the jaw-temporal joint during chewing, talking, swallowing, etc.;
• protrusion anteriorly of the incisors of the lower row during the abutment of the teeth;
• joint and muscle facial pain;
• expansion, retraction of the upper lip;
• speech disorders (lisp, illegibility);
• discomfort when biting off pieces of food.

In the absence of qualified medical care, mesial occlusion in adults causes not only changes in the facial skeleton, but also difficulties with restoration of crowns (problematic treatment, prosthetics). Dental disorders are often associated with increased stress placed on the lower dentition. Accelerated erasure of tooth enamel is observed, gum injuries, the development of gingivitis and other diseases of the oral cavity often occur. To avoid this, mesial occlusion correction should be done in childhood.

Unfortunately, the overwhelming majority of patients suffering from mesial occlusion, with age, get used to the discomfort associated with changes in the dentoalveolar apparatus, and practically do not notice the inconvenience. But it's still better to think about consulting a specialist in time and fix the problem in advance. [3]

Mesial bite in a child

The mesial bite can form even in the fetus, which is in the mother's womb - this happens as a result of the genetic characteristics of one of the parents (less often - two parents at once).

After the baby is born, the bite can be spoiled under the influence of many factors - for example, sucking the upper lip, sleeping with the head lowered to the chest, etc.

In childhood, in contrast to the adult period, the skeletal system is not yet fully formed. In this regard, any impact on the dentition is easier, and the bite is corrected faster and better. If a slight correction of the position of the dentition or individual crowns is required, then from about the age of seven, removable vestibular plates are used for treatment. For more severe mesial occlusion, braces may be required. [4]

Forms

Mesial bite is:

• jaw, or skeletal - that is, associated with abnormal bone development;
• dental, or dentoalveolar - due to improper placement of crowns in the alveolar processes.

Depending on the location, the mesial bite can be:

• general (mismatch is noted in the area of the frontal and in the area of the lateral teeth);
• partial (pathology is observed only in the frontal zone).

In addition, there is a bite without mandibular displacement, or with displacement.

According to the etiological characteristics, they speak of true and false progeny. The true mesial bite is based on the increased size of the mandibular branch and / or body. The false variant is a frontal progenic disorder or forced mesial occlusion, which develops in the absence of erasure of the tubercles of the milk mandibular canines against the background of normal jaw rows. In a calm state, the patient does not show pathological signs - until he closes his teeth: the jaw moves forward, reaching the mesial ratio. [5]

Other possible forms of pathology:

• An open mesial bite, in addition to the protrusion of the lower jaw, is characterized by a lack of contact between most of the antagonist crowns (molars or incisors).
• Cross bite is characterized by insufficient development of one of the sides of the dentition. As a result, on one jaw side, the lower teeth overlap the upper ones, and on the other - vice versa.
• The gnatic form of the mesial occlusion is determined by the change in the mandibular angles - up to 145-150.

Complications and consequences

Mesial bite refers to the pathologies of the dentoalveolar mechanism, prone to relapse. If timely measures were not taken to eliminate the defect, then such a pathology can progress, contributing to the development of more complex anomalies and diseases.

One of the most common consequences of mesial occlusion is impaired facial proportions and a lack of harmonious appearance. The patient has an unpleasant "depressed" profile due to the anterior protrusion of the lower jaw (the so-called "mesial lunge"). This type of bite can be combined with individual dental or dentoalveolar defects - for example, anterior mandibular displacement can lead to reverse overlap in the area of the anterior crowns.

The presence of a sagittal cleft can impair chewing function, as the chewing effect is reduced by lingual contact of the anterior teeth.

Chewing disorders, in turn, negatively affect the functioning of the digestive organs, as well as the functional ability of the temporomandibular joint. Various articular pathologies appear - for example, inflammatory or dystrophic in nature. [6]

Severe reverse overlap can lead to chronic damage to the periodontium, which is associated with constant contact of the anterior dentition against the mandibular gum. As a result, gingivitis, periodontal disease, and periodontitis develop.

Slight back overlap (front teeth butt-apart) often results in increased crown wear. The increased load on the chewing molars is compensated for some time, but after a while destructive processes begin.

A skeletal defect of the third Angle class leads to difficulties in carrying out orthopedic and orthodontic treatment procedures. Patients may have impaired speech and pronunciation. Often there are complaints of temporomandibular pain radiating to the area of the auricles and head, as well as joint crunch. The severity of negative consequences depends on the neglect of such a pathology as mesial occlusion. [7]

Diagnostics mesial occlusion

Diagnostic procedures for determining the features of the mesial occlusion include a variety of techniques.

Clinical examination consists of the following activities:

• conversation with the patient (listening to complaints, questioning about the existing pathology, lifestyle, childhood diseases, etc.);
• examination of the oral cavity, face, head;
• probing the maxillofacial area, articular joints;
• assessment of the functions of chewing, swallowing, speech, etc.

In many cases, the diagnosis of mesial occlusion is established already at the first examination, which is associated with characteristic clinical signs of pathology: a peculiar "depressed" profile, prominent position of the chin, and an increase in the lower facial segment draw attention to itself. The lower lip thickens, the upper lip is somewhat shortened. When the mouth is closed, the lips tighten, and the lower frontal dentition is in front of the upper row.

During the examination, the doctor examines the mucous tissues, periodontium and hard palate. There is a noticeable increase in the mandibular angle, the severity of the nasolabial folds against the background of the smoothness of the chin fold. 

Feeling the temporomandibular joint with mesial occlusion is accompanied by painful sensations.

Instrumental diagnostics includes:

• X-ray examination of the jaw mechanism (orthopantomography, teleradiography with lateral projection);
• photo of the face in front and in profile;
• taking impressions for making diagnostic models.

Orthopantomography makes it possible to assess the state of the entire dentition and hard tissues, to determine changes in the periapical zones, to find out the presence of permanent primordia at the stage of milk teeth.

Teleradiography is done to look for skeletal or soft tissue defects.

Diagnostics of the jaw system is carried out using computed tomography: the mesial bite or atypical arrangement of the articular heads is determined.

Differential diagnosis

Differential diagnosis is carried out with other types of bite. For example, according to Khoroshilkina, the gnatic type is characterized by a mismatch of the maxillary dentoalveolar arches. In the case of the dental alveolar type, a functional test is performed: the patient is offered, if possible, to bring the lower jaw posteriorly, and the doctor at this time determines the first Angle bite key. 

Distal and mesial occlusion have significant differences, therefore, their differentiation is not difficult for the doctor: with distal occlusion, the upper jaw strongly protrudes forward relative to the lower one at the time of closing the dentition. In case of mesial occlusion, the situation is the opposite: the lower jaw is extended when the upper jaw is "lagging", and the lower dentition overlaps the upper one.

Treatment mesial occlusion

There are such methods of mesial occlusion correction:

• surgical (used in difficult advanced cases);
• braces (an effective method, which, however, is not shown in all cases of mesial occlusion);
• braceless (no less effective and common method of correction).

All bracket systems have one distinctive feature - they cannot be removed on their own. That is, they can be indirectly defined as a number of non-removable correcting devices. The wearing of braces can last for about 1 to 2 years, but this period can vary greatly depending on the individual.

In general, in addition to braces, other therapeutic and corrective methods are used, which we will discuss below.

During the period of temporary occlusion, measures are taken to promote the normal development and growth of the jaw system. If maxillary development is delayed, doctors recommend:

• massage the frontal zone of the upper alveolar process;
• exclude pathology of the frenum of the tongue and disorders of muscle function (impaired swallowing, mouth breathing, etc.).

For temporary occlusion, vestibular plates with a lingual emphasis are most often used, as well as Khintz's or Schoncher's plates. Orthopedic treatment is not excluded, which consists in selective grinding with a maxillary block due to the extrusion of canines.

Surgery

In the case when the use of various orthodontic constructions does not bring the desired result, the doctor may recommend a radical solution to the problem - a surgical or orthognathic operation. Most often, the help of a surgeon is resorted to:

• with a strong imbalance of the face;
• with congenital anomalies of jaw development;
• with deformation of the alveolar processes;
• with severe speech defects;
• if it is impossible to eat adequately;
• with chin dysplasia;
• if it is impossible to tightly connect the upper lip with the lower one.

Contraindications to surgery can be diabetes, impaired blood clotting, infectious and inflammatory pathologies.

The operation to correct the mesial occlusion is carried out only after a preliminary preparatory period, which includes the examination of the patient and the creation of an individual computer model of the dentoalveolar mechanism. [8]

Correction of mesial occlusion without surgery

The devices that are used to eliminate bite anomalies are distinguished by the type of fastening and by the effect on the dentition.

• The vestibular plate is a fairly effective and convenient apparatus for mesial occlusion, which allows:
  • balance the external dimensions and development of the jaw bones;
  • normalize sky width;
  • fix the crowns in the required position.

The vestibular plate has a number of positive qualities. It even outperforms the popular bracket system in many ways:

• the plate can be removed by yourself;
• it can be worn by both children and adult patients;
• it does not interfere with brushing your teeth, and if necessary, it can be removed for a short time.

The disadvantage of the device is that it is not intended to correct pronounced mesial occlusion in adults, and the period of wearing the plate is quite long.

• Orthodontic trainers for mesial occlusion have a special purpose: their action is aimed at eliminating the cause of the violation. In general, trainers are elastic products that have a silicone base. They are used at almost any age, since adaptation to wearing occurs quickly enough. Positive aspects of using trainers:
  • they act on the cause of the defect, prevent the development of complications at any stage of correction;
  • they are safe and hypoallergenic;
  • they are worn mainly at night, and the period of daytime use is about 4 hours.

Trainers use it in stages. During the first six to eight months, the adaptation period continues, during which a soft trainer is used (for easy adaptation and correction of the jaw position). At the second stage, which lasts about the same as the previous stage, the correction is completed. For this, a rigid device is used to bring the bite closer to the normal position. [9]

According to experts, the disadvantage of this type of correction is its duration (more than a year). However, it is often practiced for its convenience, relatively low cost, and physiological nature. Trainers are comfortable and used discreetly.

• Aligners, or mouth guards for mesial occlusion are often prescribed. All this is because their use is effective, does not require a long course of therapy, is inconspicuous and convenient. The aligners act directly on the dentition. Each product is made according to individual sizes and shapes, based on the impression of the patient's teeth. Correctly designed aligners successfully correct bite without causing discomfort. It is possible to use different types of mouth guards during a therapeutic course. The main disadvantage of these devices is their high cost.

Exercises for mesial occlusion

Additional exercises to correct the mesial occlusion can be as follows:

1. Trying to breathe deeply, take a slow nasal inhalation, then the same nasal exhalation. Repeat several times.
2. They sit in front of a mirror, hold their head straight, pull their shoulders back (straighten), tighten their stomach. Knees should be bent at right angles, legs and heels connected.
3. They open their mouths, make circular movements with their tongue in one direction and the other.
4. The tongue is laid on the lower lip, and the upper one is "spanked" on top of the tongue.
5. Lead the tip of the tongue along the upper palate (over the entire surface).
6. For several minutes, the sound "d-d-d-d-d..." is practiced.
7. They open their mouths wide and click their tongue.
8. The tongue is lifted up, pressed against the upper palate. They clench their teeth, make a swallowing movement without changing the position of the tongue.
9. The tip of the tongue is pressed against the inner sides of the upper anterior dentition. Press until you feel muscle fatigue.
10. They pull their head back a little, open and close their mouth, while trying to reach the base of the hard palate with the tip of the tongue.
11. Press the lower lip with the upper incisors, hold, then release.

It is undesirable to start exercises on your own without consulting a dentist (dental orthopedist, orthodontist). Classes are not suitable for all categories of patients with mesial occlusion, therefore, prior consultation with a doctor is necessary.

Myogymnastics for mesial occlusion

In childhood, at the stage of formation of a stable mesial occlusion, the situation can be corrected by performing simple exercises. Before starting classes, it is important to remember the following rules:

• for each exercise, you should make maximum effort and muscle work;
• you need not abruptly, but gradually make the movements more intense;
• after each repetition, you should pause - about 5-6 minutes;
• it is advisable to exercise before the onset of a feeling of slight muscle fatigue

Myogymnastics usually consists of the following exercises:

1. The tip of the tongue is pressed against the gum line at the inner side of the dentition. Several repetitions are performed for five minutes.
2. They sit on a chair, tilt their head back a little, open their mouths and touch the base of the hard palate with their tongue.
3. They put the lower lip under the front upper incisors, trying to push it as far as possible into the oral cavity.
4. Slowly open and close the mouth, trying to move the lower jaw posteriorly and close the edges of the front teeth.

The listed exercises allow you to cope with moderate manifestations of mesial occlusion. However, such myogymnastics is not shown to all patients: for example, it cannot be practiced by people with severe muscular hypertrophy, third-degree malocclusion, and impaired jaw-joint function.

Classes begin in childhood, during the period of active formation of the musculo-jaw apparatus. Experts say that until the child reaches 7 years old, it is possible to correct the bite only with the help of such training. At an older age, myogymnastics classes are used only as an addition to the main orthodontic treatment.

Prevention

Heredity is a common, but not the only, cause of mesial occlusion. Often, pathology is provoked by various diseases and not the most useful habits. Based on this, doctors have identified the most effective ways to prevent this disorder:

• timely access to a doctor regarding the treatment of any diseases of the dentition;
• early visit to the dentist for any suspicious symptoms associated with temporary teeth in a child;
• eradication of bad habits in children;
• monitoring the position of the sleeping child;
• contributing to the formation of correct children's posture.

It is much easier to prevent a disease than to try to cure it for a long time later, by paying rather large sums of money for treatment.

Unfortunately, there is no specific prophylaxis for mesial occlusion. Therefore, it is necessary to carefully observe and control the state of your health in general and the dentition in particular. [10]

Forecast

Correcting mesial occlusion is not just a cosmetic task. A malocclusion with age can lead to a variety of health problems. Unevenly distributed dentoalveolar load entails damage to tooth enamel and soft tissues, early loss of teeth. Disturbances in the swallowing, respiratory function, insufficient grinding of food in the oral cavity - all these factors pose a serious danger to the body. Poorly chewed foods, when they enter the digestive tract, trigger the development of many diseases.

The first thing to do if you suspect a mesial bite is to contact your dentist and explain the problem. The doctor will carry out the necessary manipulations and determine the most optimal way to correct the occlusion.

Many people mistakenly believe that mesial occlusion can only be corrected in early childhood. This is not true. Although, of course, correction in children is faster and easier. In general, the situation can be improved in adult patients. The main thing is to trust your doctor and follow his recommendations. Only in this case can we talk about a favorable prognosis of pathology.